App crashes when implementing mute button

Question

I programmed a quiz now I set up a mediaplayer under the FOR-query, that every time the user hits a correct answer the sound will be played. Now in the same Activity I want that bttOFF will mute the sound of the Activity how can I do that? I set up an onClickListener with mp.setVolume(0,0); But the app crashes on restart. Thanks for looking! :D

         public class QuizActivity extends AppCompatActivity {

private ActionBarDrawerToggle mToggle;

private QuestionLibrary mQuestionLibrary = new QuestionLibrary();

private TextView mScoreView;
private TextView mQuestionView;
private Button mButtonChoice1;
private Button mButtonChoice2;
private Button mButtonChoice3;
private String mAnswer;
private int mScore = 0;
private int mQuestionNumber = 0;
Dialog dialog;
Dialog dialog2;
TextView closeButton;
TextView closeButton2;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_quiz);

    final MediaPlayer mp = new MediaPlayer();

    //Dialog 1
    createDialog();
    Button dialogButton = (Button) findViewById(R.id.dialogbtn);
    dialogButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            dialog.show();

        }
    });

    closeButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            dialog.dismiss();
        }
    });
    //end Dialog 1

    //Dialog 2
    createDialog2();
    Button dialogButton2 = (Button) findViewById(R.id.dialogbtn2);
    dialogButton2.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            dialog2.show();

        }
    });


    closeButton2.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            dialog2.dismiss();
        }
    });
    //end Dialog 2

    Button bttON = (Button)findViewById(R.id.bttON);

    bttON.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            mp.setVolume(0,0);


        }


    });




    TextView shareTextView = (TextView) findViewById(R.id.share);
    shareTextView.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent myIntent = new Intent(Intent.ACTION_SEND);
            myIntent.setType("text/plain");
            myIntent.putExtra(Intent.EXTRA_SUBJECT, "Hello!");
            myIntent.putExtra(Intent.EXTRA_TEXT, "My highscore in Quizzi is very high! I bet you can't beat me except you are cleverer than me. Download the app now! https://play.google.com/store/apps/details?id=amapps.impossiblequiz");
            startActivity(Intent.createChooser(myIntent, "Share with:"));
        }
    });

    mQuestionLibrary.shuffle();


    setSupportActionBar((Toolbar) findViewById(R.id.nav_action));
    DrawerLayout mDrawerLayout = (DrawerLayout) findViewById(R.id.drawerLayout);
    mToggle = new ActionBarDrawerToggle(this, mDrawerLayout, R.string.open, R.string.close);
    mDrawerLayout.addDrawerListener(mToggle);
    mToggle.syncState();
    getSupportActionBar().setDisplayHomeAsUpEnabled(true); // Able to see the Navigation Burger "Button"

    ((NavigationView) findViewById(R.id.nv1)).setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener() {
        @Override
        public boolean onNavigationItemSelected(MenuItem menuItem) {
            switch (menuItem.getItemId()) {
                case R.id.nav_stats:
                    startActivity(new Intent(QuizActivity.this, Menu2.class));
                    break;
                case R.id.nav_about:
                    startActivity(new Intent(QuizActivity.this, Menu3.class));
                    break;
            }

            return true;
        }
    });

    mScoreView = (TextView) findViewById(R.id.score_score);
    mQuestionView = (TextView) findViewById(R.id.question);
    mButtonChoice1 = (Button) findViewById(R.id.choice1);
    mButtonChoice2 = (Button) findViewById(R.id.choice2);
    mButtonChoice3 = (Button) findViewById(R.id.choice3);

    final List<Button> choices = new ArrayList<>();
    choices.add(mButtonChoice1);
    choices.add(mButtonChoice2);
    choices.add(mButtonChoice3);

    updateQuestion();



    for (final Button choice : choices) {
        choice.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View view) {
                if (choice.getText().equals(mAnswer)) {


                    try {
                        mp.reset();
                        AssetFileDescriptor afd;
                        afd = getAssets().openFd("sample.mp3");
                        mp.setDataSource(afd.getFileDescriptor(),afd.getStartOffset(),afd.getLength());
                        mp.prepare();
                        mp.start();
                    } catch (IllegalStateException e) {
                        e.printStackTrace();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                    updateScore();
                    updateQuestion();
                    Toast.makeText(QuizActivity.this, "Correct", Toast.LENGTH_SHORT).show();



                } else {
                    Toast.makeText(QuizActivity.this, "Wrong... Try again!", Toast.LENGTH_SHORT).show();

                    Intent intent = new Intent(QuizActivity.this, Menu2.class);
                    intent.putExtra("score", mScore); // pass score to Menu2
                    startActivity(intent);
                }
            }
        });
    }

}

private void updateQuestion() {
    if (mQuestionNumber < mQuestionLibrary.getLength()) {
        mQuestionView.setText(mQuestionLibrary.getQuestion(mQuestionNumber));
        mButtonChoice1.setText(mQuestionLibrary.getChoice1(mQuestionNumber));
        mButtonChoice2.setText(mQuestionLibrary.getChoice2(mQuestionNumber));
        mButtonChoice3.setText(mQuestionLibrary.getChoice3(mQuestionNumber));
        mAnswer = mQuestionLibrary.getCorrectAnswer(mQuestionNumber++);
    } else {
        Toast.makeText(QuizActivity.this, "Last Question! You are very intelligent!", Toast.LENGTH_SHORT).show();
        Intent intent = new Intent(QuizActivity.this, Menu2.class);
        intent.putExtra("score", mScore);
        startActivity(intent);
    }
}

private void updateScore() {
    mScoreView.setText(String.valueOf(++mScore));

    SharedPreferences mypref = getPreferences(MODE_PRIVATE);
    int highScore = mypref.getInt("highScore", 0);

    if (mScore > highScore) {
        SharedPreferences.Editor editor = mypref.edit();
        editor.putInt("highScore", mScore);
        editor.apply();
    }
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    return mToggle.onOptionsItemSelected(item) || super.onOptionsItemSelected(item);
}

private void createDialog() {
    dialog = new Dialog(this);
    dialog.setTitle("Tutorial");
    dialog.setContentView(R.layout.popup_menu1_1);
    closeButton = (TextView) dialog.findViewById(R.id.closeTXT);
}


private void createDialog2() {
    dialog2 = new Dialog(this);
    dialog2.setTitle("Settings");
    dialog2.setContentView(R.layout.popup_menu1_2);
   closeButton2 = (TextView) dialog2.findViewById(R.id.closeTXT2);

}

Logcat:

    Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.view.View.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
                                                                     at shapy.appz.QuizActivity.onCreate(QuizActivity.java:96)

It would be awesome I can`t find the error/ fix the Nullpointer linke 96 = bttON.setOnClickListener(new View.OnClickListener() { — Alan, Aug 09 '17 at 09:43

score 2 · Accepted Answer · answered Aug 09 '17 at 09:24

2

your get to findViewById fro your closeButton and closeButton2

answered Aug 09 '17 at 09:24

Oussema Aroua

5,225
1
24
44

I have done that in the last lines of code sir, bu the error is from the mpsetvolume.. – Alan Aug 09 '17 at 09:29
your problem is adding a `clickListener` on null view not about the mp, reread the thrown exception – Oussema Aroua Aug 09 '17 at 09:32
I am new so , could you help me sir? – Alan Aug 09 '17 at 09:38
1

bttON is null, the `R.id.bttON` is not in the same layout you are working on – Oussema Aroua Aug 09 '17 at 09:45
Yes this button is in another layout popup_menu1_2... It is a dialog which appears in this activity ah ok Iunderstand how can I implement this button from the layout in my main activity? – Alan Aug 09 '17 at 09:50
make it like closeButton inside the createDialog method – Oussema Aroua Aug 09 '17 at 09:52

score 0 · Answer 2 · answered Aug 09 '17 at 09:23

0

As shown in the documentation for the MediaPlayer class [here]( https://developer.android.com/reference/android/media/MediaPlayer.html#setVolume(float, float) ) the needed parameters are floats. You could try to do this:

public void onClick(View v) {
    mp.setVolume( 0.0, 0.0 );
}

And see if that solves your problem.

setVolume

added in API level 1

void setVolume (float leftVolume, float rightVolume)

Sets the volume on this player. This API is recommended for balancing the output of audio streams within an application. Unless you are writing an application to control user settings, this API should be used in preference to setStreamVolume(int, int, int) which sets the volume of ALL streams of a particular type. Note that the passed volume values are raw scalars in range 0.0 to 1.0. UI controls should be scaled logarithmically.

Parameters

leftVolume  float: left volume scalar

rightVolume float: right volume scalar

answered Aug 09 '17 at 09:23

AltShiftZero

385
1
16

1

it's `NullPointerException` not `IllegalArgumentexception` – Oussema Aroua Aug 09 '17 at 09:27
@OussemaAroua That comment wasn't visible when I created the answer, but you are right. – AltShiftZero Aug 09 '17 at 09:28
Does not work.. – Alan Aug 09 '17 at 09:30
no problem you have right about the setVolume too – Oussema Aroua Aug 09 '17 at 09:30
Works for me now thanks! – Alan Aug 09 '17 at 09:59

App crashes when implementing mute button

2 Answers2